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Joule thief from toroid

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nicksydney

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Hi,

I managed to salvage the attached toroid inductor (hope this is the correct term) from a PC power supply and I was reading that you can create a joule thief from a 1.5v battery, but no matter what I do I can't seem to make it work can somebody tell me what to connect where. I'm attaching the circuit that I'm following.

Can anybody tell me how to wire it up properly ?

Cheers
 
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Thats an output choke for the supply, 3.3,5,12, and negative voltages all pass through it.
Did you rewind the choke?, if not that might be your problem, 'thiefs usually need around 50 turns for both primary and feedback widings, unless you know how to calculate the turns.
If you have rewound the choke then maybe your issue is the polarity of the feedback winding, try swapping the wires over on the feedback winding.
Also there is usually a schottky diode and a capacitor for the led, but I spose it'll work as is.
 
I dont think that'll work, unless you know of people that have got it working I'd be inclined to unwind all the turns and wind 50+50 turns as per most 'thiefs have, you can unwind the main trans from the power supply to get your copper wire.

You might get away with using a smaller core, pc smps's usually have some radial chokes on the output after the rectifier diodes, these are a lot easier to wind than torroids, and for a led you dont need much of a core.

My mrs has a pocket torch I made, the core is actually an if transformer and it lights 2 leds really well.

Heres one I use a lot;
Picture 006.jpg

And heres the if can;
led2.jpg
 
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